Abstract:[Objective] Recently, researchers reported that polystyrene?eating mealworms (Tenebrio molitor) can degrade plastic and the key point might be gut microbiotia, which may open a new way to solve the global plastic pollution problem. We try to explore the structure of microbial communities in the polystyrene-eating mealworms’ gut. [Methods] Mealworms were divided into 2 groups fed with polystyrene or paper for 90 days. After that, bacterial community structure of their gut microbiota were studied by high-throughput sequencing targeting V3?V4 regions of 16S rRNA gene. PICRUSt was used to predict the community function based on their 16S rRNA gene sequences. [Results] In total, 144 258 high-quality sequences and 174 OTUs were obtained, which were classified into 111 genera in 10 phyla. The three most dominant bacterial genera in polystyrene-eating mealworms’ gut were Alcaligenes, Brevundimona and Myroides, ranked by the relative abundance. The genes related to aromatic compounds degradation were significantly enriched in the polystyrene-eating group. [Conclusion] The result indicated the diversity of bacterial community in the gut of polystyrene-eating group, which may guide the isolation of the bacteria that can degrade polystyrene.